Eratosthenes

A deep and prominent crater lying somewhat to the northeast of the larger Copernicus in the western hemisphere of the Moon's visible face, named for the great geographer who first made in accurate measurement of the Earth's circumference in the third century BCE. The crater Eratosthenes lies at the southwestern extent of the Apennine Mountains, on the border between Mare Imbrium to the north, and Sinus Aestuum (or Bay of Billows) to the southeast. The Mountains march on in a chain northeastwards from the crater, forming the southeastern edge of the Sea of Rains.

Eratosthenes has a diameter of 58km, with a central peak rising up from the crater's floor. Its terraced walls lead down nearly four kilometres to its floor, and this great depth brings it into striking relief at certain phases of the Moon (though it is by no means the deepest crater on the Moon: Newton, near the lunar south pole, is some two kilometres deeper still).